Actuated stuffing box for an artificial lift system

ABSTRACT

A stuffing box assembly for an artificial lift system includes a stuffing box including a housing having a passage, in which the housing has a shoulder disposed along the passage. The stuffing box also includes a seal disposed within the passage and engaged with the shoulder. The seal is configured to engage a polish rod while the polish rod extends through the passage, and the seal is configured to expand radially in response to longitudinal compression of the seal. In addition, the stuffing box includes an actuator having an engagement element configured to move along a longitudinal axis to compress the seal. Furthermore, the stuffing box assembly includes a controller configured to determine a flow rate of fluid bypassing the seal based on one or more input signals, and the controller is configured to control the actuator based on the flow rate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of U.S. Provisional Application Ser. No. 63/239,199, entitled “ACTUATED STUFFING BOX FOR AN ARTIFICIAL LIFT SYSTEM”, filed Aug. 31, 2021, which is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates generally to an actuated stuffing box for an artificial lift system.

Wells are drilled into reservoirs to discover and produce oil. The oil within such a reservoir may be under sufficient pressure to drive the oil through the well to the surface. However, over time, the natural pressure of the oil may decline, and an artificial lift system may be used to extract the oil from the reservoir. The artificial lift system may include a pump disposed within the reservoir and a wellhead at the surface. A tubing string may be supported by the wellhead and may extend to the reservoir, and the pump may drive the oil from the reservoir to the wellhead via the tubing string.

The pump is driven by a series of polish rods that extend through the wellhead and the tubing string to the pump. The polish rods are lifted and lowered by a pump jack, which supports the polish rods. In addition, the wellhead includes a stuffing box configured to establish a seal around a polish rod at the end of the series of polish rods. For example, the stuffing box may include a housing having a passage, the polish rod may extend through the passage, and a seal may be disposed within the passage and configured to engage the polish rod. Accordingly, the stuffing box may substantially block flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods.

Certain stuffing boxes include a port extending through the housing and positioned above the seal. Oil that bypasses the seal may flow through the port to an oil sensor configured to detect the quantity and/or rate of oil flow through the seal. If the quantity/rate of oil flow through the seal is greater than a threshold value, an automated system may inform an operator and terminate operation of the artificial lift system. The operator may then manually increase the longitudinal compression of the seal (e.g., by rotating an end cap, by rotating fastener(s), etc.), thereby increasing the contact force between the seal and the polish rod. As a result, the rate of oil flow through the seal may be substantially reduced (e.g., below the threshold value). Unfortunately, a significant amount of time may elapse between the automated system terminating operation of the artificial lift system and the operator increasing the longitudinal compression of the seal. As a result, oil production from the well may be terminated for a significant duration.

BRIEF DESCRIPTION

In certain embodiments, a stuffing box assembly for an artificial lift system includes a stuffing box. The stuffing box includes a stuffing box housing having a passage extending through an entire longitudinal extent of the stuffing box housing, in which the stuffing box housing has a shoulder disposed along the passage. The stuffing box also includes a seal disposed within the passage of the stuffing box housing and engaged with the shoulder. The seal is configured to engage a polish rod while the polish rod extends through the passage, and the seal is configured to expand radially in response to compression of the seal along a longitudinal axis of the stuffing box. In addition, the stuffing box includes an actuator having an engagement element configured to move along the longitudinal axis to compress the seal. Furthermore, the stuffing box assembly includes a controller having a processor and a memory. The controller is communicatively coupled to the actuator, the controller is configured to determine a flow rate of fluid bypassing the seal based on one or more input signals, and the controller is configured to control the actuator based on the flow rate of the fluid bypassing the seal.

DRAWINGS

These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a side view of an embodiment of an artificial lift system having a wellhead;

FIG. 2 is a side view of a portion of the artificial lift system of FIG. 1 , including the wellhead and a polish rod connection assembly;

FIG. 3 is a perspective view of an embodiment of a stuffing box assembly that may be employed within the wellhead of FIG. 1 ;

FIG. 4 is a cross-sectional view of a stuffing box of the stuffing box assembly of FIG. 3 ;

FIG. 5 is a perspective view of another embodiment of a stuffing box assembly that may be employed within the wellhead of FIG. 1 ;

FIG. 6 is a cross-sectional view of a stuffing box of the stuffing box assembly of FIG. 5 , taken along line 6-6 of FIG. 5 ; and

FIG. 7 is another cross-sectional view of the stuffing box of the stuffing box assembly of FIG. 5 , taken along line 7-7 of FIG. 5 .

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments.

FIG. 1 is a side view of an embodiment of an artificial lift system 10 having a wellhead 12. As illustrated, the artificial lift system 10 includes a pump 14 disposed within a reservoir 16. In addition, the wellhead 12 is positioned at the surface 18. A tubing string 20, which is supported by the wellhead 12, extends from the surface 18 to the reservoir 16. The pump 14 is configured to drive oil from the reservoir 16 to the surface 18 via the tubing string 20 and the wellhead 12.

The pump 14 is driven by a series of polish rods that extend through the tubing string 20 to the pump 14. As illustrated, a polish rod 22 at the end of the series of polish rods is coupled to a pump jack 24 of the artificial lift system 10. The pump jack 24 is configured to lift and lower the polish rods, thereby driving the pump 14. One or more polish rods may contact the tubing string 20 at one or more points along a circumference of the polish rod(s). Accordingly, as the polish rods are driven to move within the tubing string 20, certain point(s) on the polish rod(s) may wear. In the illustrated embodiment, a rod rotator assembly 26 is configured to drive the polish rods to rotate within the tubing string 20, thereby distributing the wear around the circumference of the polish rod(s). As a result, the longevity of the polish rod(s) may be increased. As discussed in detail below, the rod rotator assembly 26 is supported by a carrier (e.g., carrier bar) that is supported by the pump jack 24 via one or more cables. For example, the rod rotator assembly 26 may include a housing supported by the carrier of the artificial lift system 10. In addition, the rod rotator assembly 26 may include a top cap configured to rotate relative to the housing, in which the top cap is configured to support the polish rod 22 (e.g., via a polish rod clamp).

Furthermore, as discussed in detail below, the wellhead 12 includes a stuffing box assembly having a stuffing box configured to establish a seal around the polish rod 22 that substantially blocks flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods. In certain embodiments, the stuffing box of the stuffing box assembly includes a stuffing box housing having a passage extending through an entire longitudinal extent of the stuffing box housing. In addition, the stuffing box housing has a shoulder disposed along the passage. The stuffing box also includes a seal disposed within the passage of the stuffing box housing and engaged with the shoulder. The seal is configured to engage the polish rod (e.g., the polish rod at the end of the series of polish rods) while the polish rod extends through the passage, and the seal is configured to expand radially in response to compression of the seal along a longitudinal axis of the stuffing box. Furthermore, the stuffing box includes an actuator having an engagement element configured to move along the longitudinal axis to compress the seal. In addition, the stuffing box assembly includes a controller having a processor and a memory. The controller is communicatively coupled to the actuator, the controller is configured to determine a flow rate of fluid (e.g., oil) bypassing the seal based on one or more input signals, and the controller is configured to control the actuator based on the flow rate of the fluid bypassing the seal. For example, in response to determining the flow rate of the fluid bypassing the seal is greater than a threshold flow rate, the controller may control the actuator to compress the seal, thereby increasing the contact force between the seal and the polish rod. As a result, the flow rate of the fluid bypassing the seal may be reduced below the threshold flow rate. Because the flow rate of the fluid bypassing the seal may be automatically reduced below the threshold flow rate, the artificial lift system may operate continuously, thereby increasing the production from the well (e.g., as compared to a process that includes terminating operation of the artificial lift system in response to determining the flow rate of the fluid bypassing the seal is greater than the threshold flow rate).

FIG. 2 is a side view of a portion of the artificial lift system 10 of FIG. 1 , including the wellhead 12 and a polish rod connection assembly 28. In the illustrated embodiment, the wellhead 12 includes a tubing spool 30 that supports the tubing string (e.g., via a tubing hanger coupled to an end of the tubing string and engaged with the tubing spool). The wellhead 12 also includes a pumping tee 32 coupled to the tubing spool 30 and to a flowline 34. The pumping tee 32 is configured to receive oil from the tubing spool 30 and to control the flow of the oil through the flowline 34. The flowline 34 may extend to a storage or processing facility. Furthermore, the wellhead 12 includes a stuffing box assembly 36 having a stuffing box 38 coupled to the pumping tee 32. As previously discussed, the stuffing box 38 is configured to establish a seal around the polish rod 22 that substantially blocks flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods. While the wellhead 12 includes the tubing spool 30, the pumping tee 32, and the stuffing box assembly 36 in the illustrated embodiment, the wellhead may include other and/or additional components in other embodiments.

The polish rod connection assembly 28 includes the rod rotator assembly 26, which is configured to drive the polish rod 22 to rotate relative to the wellhead 12 and the tubing string. The polish rod connection assembly 28 also includes a carrier 40 (e.g., carrier bar) configured to support the rod rotator assembly 26. The carrier 40 may be coupled to the pump jack by one or more cables. In addition, the polish rod connection assembly 28 includes one or more polish rod clamps 42 configured to non-movably couple to the polish rod 22. The polish rod clamps 42 transfer the load (e.g., substantially vertical load) of the polish rods to the rod rotator assembly 26, the load flows through the rod rotator assembly 26 to the carrier 40, and the load applied to the carrier is transferred to the pump jack via the cable(s). Accordingly, during an upward movement of the pump jack, the pump jack lifts the carrier 40 via the cable(s), the carrier 40 drives the rod rotator assembly 26 to move upwardly, and the rod rotator assembly 26 drives the polish rods to move upwardly via engagement of the rod rotator assembly 26 with the polish rod clamp(s) 42. During a downward movement of the pump jack, the pump jack drives the polish rod 22 downwardly. Because the polish rod clamp(s) 42 are non-movably coupled to the polish rod 22, the polish rod clamp(s) 42 drive the rod rotator assembly 26 to move downwardly, thereby driving the carrier 40 to move downwardly.

FIG. 3 is a perspective view of an embodiment of a stuffing box assembly 36 that may be employed within the wellhead of FIG. 1 . As previously discussed, the stuffing box assembly 36 includes a stuffing box 38 configured to establish a seal around the polish rod (e.g., the polish rod at the end of the series of polish rods) that substantially blocks flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods. In the illustrated embodiment, the stuffing box 38 includes a stuffing box housing 44 having a passage extending through an entire longitudinal extent of the stuffing box housing 44 (e.g., the entire extent of the stuffing box housing 44 along a longitudinal axis 46). Furthermore, as discussed in detail below, the stuffing box housing 44 has a shoulder disposed along the passage. A seal is disposed within the passage and engaged with the shoulder. The seal is configured to engage the polish rod while the polish rod extends through the passage, and the seal is configured to expand radially in response to compression of the seal along the longitudinal axis 46 of the stuffing box 38.

In the illustrated embodiment, the stuffing box housing 44 has threads 48 configured to engage corresponding threads within a body of the pumping tee or another suitable component of the artificial lift system to couple the stuffing box 38 to the pumping tee/other suitable component. While the stuffing box housing 44 includes threads in the illustrated embodiment, in other embodiments, the stuffing box housing may include another suitable structure to facilitate coupling the stuffing box to the pumping tee or another suitable component of the artificial lift system. For example, in certain embodiments, the stuffing box housing may include a flange configured to interface with a corresponding flange of the pumping tee/other suitable component.

As discussed in detail below, the stuffing box 38 includes an actuator assembly 49 having an actuator and an actuator housing 50. The actuator includes an engagement element configured to move along the longitudinal axis 46 to compress the seal. A portion of the actuator is disposed within the actuator housing 50, and the actuator housing 50 is coupled to the stuffing box housing 44. In the illustrated embodiment, the actuator housing 50 is coupled to the stuffing box housing 44 by a threaded connection, in which internal threads of the actuator housing are engaged with corresponding external threads of the stuffing box housing. However, in other embodiments, external threads of the actuator housing may be engaged with internal threads of the stuffing box housing. In addition, in certain embodiments, the actuator housing may be coupled to the stuffing box housing via other suitable type(s) of connection(s) (e.g., alone or in combination with the threaded connection), such as fasteners coupling a flange of the actuator housing to a flange of the stuffing box housing, other suitable type(s) of connection(s), or a combination thereof. Furthermore, in certain embodiments, the actuator housing and the stuffing box housing may be formed as a single component.

In the illustrated embodiment, the stuffing box 38 includes an actuator cap 52 coupled to the actuator housing 50 via fasteners 54. The actuator cap 52 is configured to retain the actuator within the actuator housing. While the actuator cap is coupled to the actuator housing via fasteners in the illustrated embodiment, in other embodiments, the actuator cap may be coupled to the actuator housing via other suitable type(s) of connection(s) (e.g., alone or in combination with the fastener connection), such as a threaded connection, other suitable type(s) of connection(s), or a combination thereof.

Furthermore, as discussed in detail below, the stuffing box 38 includes a secondary seal disposed within a circumferential recess of the actuator. The secondary seal is configured to engage the polish rod while the polish rod extends through the passage of the stuffing box housing, and the secondary seal is configured to expand radially in response to compression of the secondary seal along the longitudinal axis 46 of the stuffing box. In the illustrated embodiment, the stuffing box 38 includes a packing nut 56 having external threads. The actuator has corresponding internal threads configured to engage the external threads of the packing nut 56, and the packing nut 56 is configured to compress the secondary seal along the longitudinal axis 46 in response to rotation of the packing nut 56 along a circumferential axis 58 of the stuffing box 38. The secondary seal is configured to substantially block oil that bypasses the primary seal, thereby substantially blocking flow of oil through the polish rod/stuffing box interface.

In the illustrated embodiment, the stuffing box assembly 36 includes a controller 60 communicatively coupled to the actuator. The controller 60 may be positioned at any suitable location remote from the stuffing box 38, coupled to the stuffing box 38, or disposed within the stuffing box. The controller 60 is configured to determine a flow rate of fluid (e.g., oil) bypassing the seal (e.g., primary seal) based on one or more input signals, and the controller 60 is configured to control the actuator based on the flow rate of the fluid bypassing the seal. In certain embodiments, the controller 60 is an electronic controller having electrical circuitry configured to control the actuator. In the illustrated embodiment, the controller 60 includes a processor, such as the illustrated microprocessor 62, and a memory device 64. The controller 60 may also include one or more storage devices and/or other suitable components. The processor 62 may be used to execute software, such as software for controlling the actuator, and so forth. Moreover, the processor 62 may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICs), or some combination thereof. For example, the processor 62 may include one or more reduced instruction set (RISC) processors.

The memory device 64 may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory device 64 may store a variety of information and may be used for various purposes. For example, the memory device 64 may store processor-executable instructions (e.g., firmware or software) for the processor 62 to execute, such as instructions for controlling the actuator, and so forth. The storage device(s) (e.g., nonvolatile storage) may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The storage device(s) may store data, instructions (e.g., software or firmware for controlling the actuator, etc.), and any other suitable data.

In the illustrated embodiment, the stuffing box assembly 36 includes a user interface 66 communicatively coupled to the controller 60. The user interface 66 is configured to provide information to an operator and, in certain embodiments, receive input from the operator. The user interface 66 may include any suitable input device(s) for receiving input, such as a keyboard, a mouse, button(s), switch(es), knob(s), other suitable input device(s), or a combination thereof. In addition, the user interface 66 may include any suitable output device(s) for presenting information to the operator, such as a speaker, indicator light(s), other suitable output device(s), or a combination thereof. In the illustrated embodiment, the user interface 66 includes a display 68 configured to present visual information to the operator. In certain embodiments, the display 68 may include a touchscreen interface configured to receive input from the operator.

In the illustrated embodiment, the stuffing box assembly 36 includes a sensor 70 communicatively coupled to the controller 60. As discussed in detail below, the sensor 70 is fluidly coupled to a cavity configured to receive the fluid (e.g., oil) bypassing the seal (e.g., primary seal). The sensor 70 is also configured to output an input signal to the controller 60 indicative of a flow rate of the fluid (e.g., oil) bypassing the seal (e.g., primary seal). The controller 60 is configured to receive the input signal, to determine the flow rate of the fluid bypassing the seal based on the input signal, and to control the actuator based on the flow rate of the fluid bypassing the seal. The sensor 70 may include any suitable type of sensor configured to monitor the flow rate of the fluid bypassing the seal, such as a flow sensor. Furthermore, in certain embodiments, the sensor may include a container configured to receive the fluid bypassing the seal and a level sensor configured to output (e.g., at fixed time intervals) input signals indicative of the level of the fluid within the container. The controller may receive the input signals, determine the flow rate of the fluid bypassing the seal based on the input signals (e.g., based on the change in the level of fluid within the container as a function of time), and control the actuator based on the flow rate of the fluid bypassing the seal.

In the illustrated embodiment, the stuffing box assembly 36 includes an actuating line 72 coupled (e.g., electrically coupled or fluidly coupled) to the actuator and configured to facilitate control of the actuator from a location remote from the stuffing box 38. For example, in certain embodiments, the actuator may include an electromechanical actuator (e.g., including an electric motor, a screw drive mechanism, an electric linear actuator, etc.). In such embodiments, the actuating line 72 may include an electrical line directly communicatively coupling the actuator to the controller 60. In other embodiments, the actuating line may include an actuating fluid line (e.g., pneumatic line, hydraulic line, etc.) configured to facilitate fluid flow to the actuator. In such embodiments, the controller may be communicatively coupled to the actuator via a valve assembly configured to control fluid flow to the actuator. In embodiments in which the controller is coupled to the stuffing box or disposed within the stuffing box, the actuating line may be omitted.

In the illustrated embodiment, the actuator includes a hydraulic piston, and the actuating line 72 includes a hydraulic line. The hydraulic line is configured to enable flow of hydraulic fluid to the actuator to drive the piston to move the engagement element along the longitudinal axis 46 to compress the seal. In addition, the stuffing box assembly 36 includes a valve assembly 74 fluidly coupled to the hydraulic line and communicatively coupled to the controller 60. The controller 60 is configured to control the valve assembly 74 to control flow of the hydraulic fluid from a fluid source 76 (e.g., including a pump and a reservoir) to the actuator. For example, the controller 60 may control the valve assembly 74 based on the flow rate of the fluid (e.g., oil) bypassing the seal (e.g., primary seal) to control the actuator.

In certain embodiments, the controller 60 is configured to control the actuator to compress the seal (e.g., primary seal) in response to determining the flow rate of the fluid (e.g., oil) bypassing the seal is greater than a threshold flow rate. For example, in response to determining the flow rate is greater than the threshold flow rate, the controller 60 may control the valve assembly 74 to enable hydraulic fluid flow from the fluid source 76 to the actuator. As a result, the actuator may drive the engagement element to move along the longitudinal axis 46 to compress the seal. The seal, in response to the longitudinal compression, may expand radially (e.g., along a radial axis 78 of the stuffing box 38), thereby increasing the contact force between the seal and the polish rod. Accordingly, the flow rate of the fluid bypassing the seal may decrease below the threshold flow rate. In certain embodiments, in response to determining the flow rate is less than or equal to the threshold flow rate, the controller 60 may control the valve assembly 74 to block hydraulic fluid flow from the fluid source 76 to the actuator, thereby substantially maintaining the compression of the seal.

Furthermore, in certain embodiments, the controller may determine a target contact force between the engagement element and the seal or a target hydraulic fluid pressure at the actuator based on the flow rate of the fluid (e.g., oil) bypassing the seal (e.g., primary seal). For example, the target contact force/hydraulic fluid pressure may be higher for a higher flow rate, and the target contact force/hydraulic fluid pressure may be lower for a lower flow rate. The controller may control the valve assembly to achieve the target contact force/hydraulic fluid pressure (e.g., based on feedback from an engagement element position sensor, based on feedback from a hydraulic fluid pressure sensor, based on feedback from a force sensor, based on a hydraulic fluid pressure/valve position relationship stored within the controller, based on a contact force/valve position relationship stored within the controller, etc.). In addition, in certain embodiments, the hydraulic fluid pressure at the actuator may be manually controlled (e.g., alone or in combination with the automatic control provided by the controller). For example, an operator at a remote location may manually control the valve assembly (e.g., via a lever, a knob, a button, etc.) to control hydraulic fluid flow to the actuator (e.g., based on information indicative of the flow rate of the fluid bypassing the seal, which may be presented by the user interface). Additionally or alternatively, an operator at a remote location may provide input to the user interface indicative of instructions to control the hydraulic fluid flow to the actuator (e.g., based on information indicative of the flow rate of the fluid bypassing the seal, which may be presented by the user interface). While automatic and manual control is disclosed above with reference to controlling an actuator having a hydraulic piston, the techniques associated with the automatic and manual control may apply to an actuator having a pneumatic piston. Furthermore the techniques associated with the automatic and manual control disclosed above may apply to an electromechanical actuator (e.g., in which the controller directly controls the electromechanical actuator).

FIG. 4 is a cross-sectional view of the stuffing box 38 of the stuffing box assembly of FIG. 3 . As previously discussed, the stuffing box housing 44 has a passage 80 extending through an entire longitudinal extent of the stuffing box housing 44 (e.g., extent of the stuffing box housing 44 along the longitudinal axis 46). As illustrated, the passage 80 extends along the longitudinal axis 46 of the stuffing box 38. In the illustrated embodiment, the passage 80 has a circular cross-sectional shape. However, in other embodiments, the passage may have any other suitable cross-sectional shape (e.g., elliptical, polygonal, etc.). Furthermore, the stuffing box housing 44 has a shoulder 82 disposed along the passage 80.

As previously discussed, a seal 84 (e.g., primary seal) is disposed within the passage 80 of the stuffing box housing 44 and engaged with the shoulder 82. As used herein with regard to the shoulder, “engaged” refers to direct contact between the seal and the shoulder, or indirect contact between the seal and the shoulder, in which other element(s) are disposed between the seal and the shoulder. The shoulder 82 is configured to block movement of the seal 84 along the longitudinal axis 46 toward the threads 48 of the stuffing box housing 44. The seal 84 is configured to engage the polish rod (e.g., the polish rod at the end of the series of polish rods) while the polish rod extends through the passage 80. In the illustrated embodiment, the seal 84 is configured to extend along the circumferential axis 58 about an entire circumferential extent of the polish rod. In addition, the seal 84 is configured to expand radially (e.g., along the radial axis 78) in response to compression of the seal 84 along the longitudinal axis 46. Furthermore, the seal 84 may include any suitable number of seal elements (e.g., 1, 2, 3, 4, 5, 6, 7, 8, or more) stacked on one another along the longitudinal axis 46. In certain embodiments, each seal element has an annular shape and extends about the internal circumferential extent of the stuffing box housing. In addition, each seal element may be formed from any suitable material (e.g., polymeric material, rubber, etc.) configured to expand along the radial axis 78 in response to compression along the longitudinal axis 46. In certain embodiments, each seal element is formed as a single annular piece configured to extend about the internal circumferential extent of the stuffing box housing. However, in other embodiments, at least one seal element may be formed from multiple circumferential elements that collectively form the annular seal element. During operation of the artificial lift system, the polish rod may move upwardly and downwardly through the passage 80, and the seal 84 may engage the polish rod to substantially block flow of oil through the polish rod/stuffing box interface while enabling the polish rod to move upwardly and downwardly.

In certain embodiments, the stuffing box may include a flapper assembly positioned below the seal (e.g., primary seal) along the longitudinal axis. The flapper assembly may include a flapper carrier and a flapper pivotally coupled to the flapper carrier. The flapper may be biased toward the flapper carrier. Accordingly, while the polish rod is not disposed within the passage of the stuffing box housing, the flapper may be driven to rotate to a closed position that substantially blocks oil flow through the passage. In addition, while the polish rod is disposed within the passage (e.g., during operation of the artificial lift system), the polish rod may maintain the flapper in an open position. In certain embodiments, the flapper carrier may be positioned between the seal and the shoulder of the stuffing box housing.

As previously discussed, the stuffing box 38 includes an actuator assembly 49 having an actuator 86 and an actuator housing 50, in which a portion of the actuator 86 is disposed within the actuator housing 50. The actuator 86 has an engagement element 88 configured to move along the longitudinal axis 46 (e.g., in a direction toward the threads 48 of the stuffing box housing 44) to compress the seal 84. As previously discussed, the seal 84 is configured to expand radially (e.g., along the radial axis 78) in response to compression of the seal 84 along the longitudinal axis 46, thereby increasing a contact force between the seal 84 and the polish rod. In the illustrated embodiment, the engagement element 88 extends about the entire circumferential extent of the seal 84 (e.g., extent of the seal 84 along the circumferential axis 58), thereby enabling the engagement element 88 to apply a substantially even force to a longitudinal end of the seal 84.

In the illustrated embodiment, the actuator 86 includes a hydraulic piston 90, and the actuating line 72 includes a hydraulic line. As illustrated, the actuating/hydraulic line is coupled to the actuator housing 50 and fluidly coupled to a port 92 extending through the actuator housing 50. The port 92 is fluidly coupled to a first annular cavity 94 positioned on a first longitudinal side of the piston 90. The first annular cavity 94 is formed by the piston 90, the actuator housing 50, and the actuator cap 52. In addition, the stuffing box 38 includes a cavity seal 96 disposed between the piston 90 and the actuator housing 50, and the stuffing box 38 includes a cavity seal 96 disposed between the actuator 86 and the actuator cap 52. The cavity seals 96 are configured to substantially block fluid flow out of the first annular cavity 94. As previously discussed, the controller is configured to control the valve assembly to control flow of the hydraulic fluid from the fluid source to the actuator 86. The hydraulic fluid from the fluid source flows into the first annular cavity 94, thereby driving the piston 90 to move the engagement element 88 along the longitudinal axis 46 to compress the seal 84, thereby increasing the contact force between the seal 84 and the polish rod. In the illustrated embodiment, the engagement element 88 is integrally formed with the piston 90. However, in other embodiments, the engagement element and the piston may be formed separately and coupled to one another.

While the first cavity is annular in the illustrated embodiment, in other embodiments, the first cavity may have another suitable shape. In addition, while the actuating line 72 includes a single hydraulic line and the stuffing box 38 includes a single first cavity 94 in the illustrated embodiment, in other embodiments, the stuffing box may include multiple first cavities (e.g., cavities positioned on the first longitudinal side of the piston) and a hydraulic line may extend to each cavity. Furthermore, while the illustrated actuator includes a hydraulic piston in the illustrated embodiment, in other embodiments, the actuator may include a pneumatic piston. In such embodiments, the actuating line may include a pneumatic line configured to provide air to the actuator. In addition, in certain embodiments, the actuator may include an electromechanical actuator (e.g., including an electric motor, a screw drive mechanism, an electric linear actuator, etc.). In such embodiments, the actuating line may include an electrical line directly communicatively coupled to the controller.

As previously discussed, in certain embodiments, the actuator housing 50 is coupled to the stuffing box housing 44 by a threaded connection. In such embodiments, rotation of the actuator housing may drive the engagement element of the actuator to compress the seal while substantially no fluid is present within the first annular cavity. For example, during an initial seal compression process (e.g., before operation of the actuator), substantially no fluid may be present within the annular cavity. Accordingly, the actuator housing may be rotated to drive the actuator cap to move the actuator along the longitudinal axis toward the seal. As a result, the engagement element of the actuator may establish an initial compression of the seal, thereby substantially establishing a target contact force between the seal and the polish rod. In response to the flow rate of fluid (e.g., oil) bypassing the seal (e.g., primary seal) being greater than a threshold flow rate, the controller may control the actuator to compress the seal, thereby increasing the contact force between the seal and the polish rod.

In the illustrated embodiment, a second annular cavity 98 is positioned on a second longitudinal side of the piston 90, opposite the first longitudinal side. The second annular cavity 98 is formed by the piston 90, the engagement element 88, the stuffing box housing 44, the seal 84, and the actuator housing 50. The second annular cavity 98 is configured to receive fluid (e.g., oil) bypassing the seal 84. As illustrated, the sensor is fluidly coupled to the second annular cavity 98 via a port 100 extending through the actuator housing 50. As previously discussed, the sensor is configured to output input signal(s) to the controller.

In the illustrated embodiment, the stuffing box 38 includes a secondary seal 102 (e.g., including one or more secondary seal elements) disposed within a circumferential recess 104 of the actuator 86. In addition, the secondary seal 102 is engaged with a shoulder 106 of the actuator 86 to block movement of the secondary seal 102 along the longitudinal axis 46 toward the threads 48 of the stuffing box housing 44. As used herein with regard to the shoulder, “engaged” refers to direct contact between the secondary seal and the shoulder, or indirect contact between the secondary seal and the shoulder, in which other element(s) are disposed between the secondary seal and the shoulder. The secondary seal 102 is configured to engage the polish rod (e.g., the polish rod at the end of the series of polish rods) while the polish rod extends through the passage 80 of the stuffing box housing 44. In addition, the secondary seal 102 is configured to expand radially in response to compression of the secondary seal along the longitudinal axis 46 of the stuffing box 38.

In the illustrated embodiment, the packing nut 56 of the stuffing box 38 has external threads 108. In addition, the actuator 86 has corresponding internal threads 110 configured to engage the external threads 108 of the packing nut 56. The packing nut 56 is configured to compress the secondary seal 102 along the longitudinal axis 46 in response to rotation of the packing nut 56 along the circumferential axis 58. In addition, because the packing nut 56 couples the secondary seal 102 to the actuator 86, the secondary seal 102 and the packing nut 56 move with the actuator 86 along the longitudinal axis 46. While the packing nut has external threads and the actuator has internal threads in the illustrated embodiment, in other embodiments, the packing nut may have internal threads and the actuator may have external threads. Furthermore, while the packing nut is coupled to the actuator by a threaded connection in the illustrated embodiment, in other embodiments, the packing nut may be coupled to the actuator by a fastener connection or by another suitable type of connection. In addition, while the stuffing box 38 includes the secondary seal 102 in the illustrated embodiment, in other embodiments, the secondary seal may be omitted.

FIG. 5 is a perspective view of another embodiment of a stuffing box assembly 36′ that may be employed within the wellhead of FIG. 1 . In the illustrated embodiment, the stuffing box assembly 36′ includes a stuffing box 38′ configured to establish a seal around the polish rod (e.g., the polish rod at the end of the series of polish rods) that substantially blocks flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods. The stuffing box 38′ includes a stuffing box housing 114 having a passage extending through an entire longitudinal extent of the stuffing box housing 114 (e.g., the entire extent of the stuffing box housing 114 along the longitudinal axis 46). Furthermore, as discussed in detail below, the stuffing box housing 114 has a shoulder disposed along the passage. A seal is disposed within the passage and engaged with the shoulder. The seal is configured to engage the polish rod while the polish rod extends through the passage, and the seal is configured to expand radially in response to compression of the seal along the longitudinal axis 46 of the stuffing box 38′.

In the illustrated embodiment, the stuffing box housing 114 has threads 116 configured to engage corresponding threads within a body of the pumping tee or another suitable component of the artificial lift system to couple the stuffing box 38′ to the pumping tee/other suitable component. While the stuffing box housing 114 includes threads in the illustrated embodiment, in other embodiments, the stuffing box housing may include another suitable structure to facilitate coupling the stuffing box to the pumping tee or another suitable component of the artificial lift system. For example, in certain embodiments, the stuffing box housing may include a flange configured to interface with a corresponding flange of the pumping tee/other suitable component.

In the illustrated embodiment, the stuffing box 38′ includes an actuator assembly 118 having an actuator 119 and an actuator housing 120. The actuator 119 includes an engagement element configured to move along the longitudinal axis 46 to compress the seal. In addition, a portion of the actuator 119 (e.g., a gear assembly) is disposed within the actuator housing 120, and the actuator housing 120 is coupled to the stuffing box housing 114. In the illustrated embodiment, the actuator housing 120 is coupled to the stuffing box housing 114 by a threaded connection, in which internal threads of the actuator housing are engaged with corresponding external threads of the stuffing box housing. However, in other embodiments, external threads of the actuator housing may be engaged with internal threads of the stuffing box housing. In addition, in certain embodiments, the actuator housing may be coupled to the stuffing box housing via other suitable type(s) of connection(s) (e.g., alone or in combination with the threaded connection), such as fasteners coupling a flange of the actuator housing to a flange of the stuffing box housing, other suitable type(s) of connection(s), or a combination thereof. Furthermore, in certain embodiments, the actuator housing and the stuffing box housing may be formed as a single component.

In the illustrated embodiment, the actuator housing 120 includes a body 122 and an end cap 124. The internal threads of the actuator housing 120 are formed on the end cap 124, and the end cap 124 is coupled to the body 122 via fasteners 126. While the end cap 124 is coupled to the body 122 via fasteners 126 in the illustrated embodiment, in other embodiments, the actuator housing end cap may be coupled to the actuator housing body via other suitable type(s) of connection(s) (e.g., alone or in combination with the fastener connection), such as a threaded connection, other suitable type(s) of connection(s), or a combination thereof. Furthermore, while the actuator housing is formed from two components (e.g., the body and the end cap) in the illustrated embodiment, in other embodiments, the actuator housing may be formed from more or fewer components (e.g., 1, 3, 4, or more). For example, in certain embodiments, the actuator housing may be formed as a single component.

In the illustrated embodiment, the stuffing box 38′ includes an actuator cap 128 coupled to the actuator housing 120 via a threaded connection, in which external threads of the actuator cap 128 are engaged with corresponding internal threads of the actuator housing 120. However, in other embodiments, internal threads of the actuator cap may be engaged with external threads of the actuator housing. The actuator cap 128 is configured to retain a portion of the actuator 119 within the actuator housing 120. While the actuator cap is coupled to the actuator housing via a threaded connection in the illustrated embodiment, in other embodiments, the actuator cap may be coupled to the actuator housing via other suitable type(s) of connection(s) (e.g., alone or in combination with the threaded connection), such as a fastener connection, other suitable type(s) of connection(s), or a combination thereof

Furthermore, as discussed in detail below, the stuffing box 38′ includes a secondary seal disposed within a circumferential recess of the engagement element of the actuator 119. The secondary seal is configured to engage the polish rod while the polish rod extends through the passage of the stuffing box housing, and the secondary seal is configured to expand radially in response to compression of the secondary seal along the longitudinal axis 46 of the stuffing box. In the illustrated embodiment, the stuffing box 38′ includes a packing driver 130 having multiple apertures. Threaded fasteners 132 extend through the apertures and engage respective threaded recesses within the engagement element of the actuator 119. Each threaded fastener 132 is configured to drive the packing driver 130 to compress the secondary seal along the longitudinal axis 46 in response to rotation of the threaded fastener 132. The secondary seal is configured to substantially block oil that bypasses the primary seal, thereby substantially blocking flow of oil through the polish rod/stuffing box interface.

In the illustrated embodiment, the actuator 119 includes an electric motor 134 (e.g., rotary actuator) configured to drive a shaft 136 of the electric motor 134 in rotation. The actuator 119 also includes a gear assembly disposed within the actuator housing 120 and configured to translate rotational motion of the shaft 136 into linear movement of the engagement element. Accordingly, the electric motor 134 is configured to drive the engagement element, via the gear assembly, to move along the longitudinal axis 46 to compress the seal. While the actuator 119 includes an electric motor 134 in the illustrated embodiment, in other embodiments, the actuator 119 may include another suitable type of rotary actuator, such as a pneumatic motor or a hydraulic motor. Furthermore, in certain embodiments, a casing of the rotary actuator (e.g., the electric motor 134) may be coupled to the actuator housing 120 and/or to another suitable component of the stuffing box assembly 36′ that blocks rotation of the casing, thereby enabling the shaft to drive the gear assembly to move the engagement element along the longitudinal axis to compress the seal.

As previously discussed with regard to the stuffing box assembly 36 disclosed above with reference to FIGS. 3-4 , the stuffing box assembly 36′ includes the controller 60 communicatively coupled to the actuator 119. The controller 60 may be positioned at any suitable location remote from the stuffing box 38′, coupled to the stuffing box 38′, or disposed within the stuffing box. The controller 60 is configured to determine a flow rate of fluid (e.g., oil) bypassing the seal (e.g., primary seal) based on one or more input signals, and the controller 60 is configured to control the actuator 119 based on the flow rate of the fluid bypassing the seal. Furthermore, the stuffing box assembly 36′ includes the user interface 66 communicatively coupled to the controller 60. As previously discussed, the user interface 66 is configured to provide information to an operator and, in certain embodiments, receive input from the operator.

As previously discussed with regard to the stuffing box assembly 36 disclosed above with reference to FIGS. 3-4 , the stuffing box assembly 36′ includes the sensor 70 communicatively coupled to the controller 60. As discussed in detail below, the sensor 70 is fluidly coupled to a cavity configured to receive the fluid (e.g., oil) bypassing the seal (e.g., primary seal). The sensor 70 is also configured to output an input signal to the controller 60 indicative of a flow rate of the fluid (e.g., oil) bypassing the seal (e.g., primary seal). The controller 60 is configured to receive the input signal, to determine the flow rate of the fluid bypassing the seal based on the input signal, and to control the actuator 119 based on the flow rate of the fluid bypassing the seal. As previously discussed, the sensor 70 may include any suitable type of sensor configured to monitor the flow rate of the fluid bypassing the seal, such as a flow sensor. Furthermore, in certain embodiments, the sensor may include a container configured to receive the fluid bypassing the seal and a level sensor configured to output (e.g., at fixed time intervals) input signals indicative of the level of the fluid within the container. The controller may receive the input signals, determine the flow rate of the fluid bypassing the seal based on the input signals (e.g., based on the change in the level of fluid within the container as a function of time), and control the actuator based on the flow rate of the fluid bypassing the seal.

The stuffing box assembly 36′ includes an actuating line 72′ coupled (e.g., electrically coupled or fluidly coupled) to the actuator 119 and configured to facilitate control of the actuator 119 from a location remote from the stuffing box 38. In the illustrated embodiment, the actuating line 72′ includes an electrical line directly communicatively coupling the electric motor 134 of the actuator 119 to the controller 60. The electrical line is configured to provide electrical power to the electric motor 134, and the electric motor 134 is configured to drive the engagement element to move along the longitudinal axis to compress the seal in response to receiving the electrical power. However, as previously discussed, in other embodiments, the actuating line may include an actuating fluid line (e.g., pneumatic line, hydraulic line, etc.) configured to facilitate fluid flow to the actuator (e.g., pneumatic motor, hydraulic motor, etc.). In such embodiments, the controller may be communicatively coupled to the actuator via a valve assembly configured to control fluid flow to the actuator. In embodiments in which the controller is coupled to the stuffing box or disposed within the stuffing box, the actuating line may be omitted.

In certain embodiments, the controller 60 is configured to control the actuator 119 to compress the seal (e.g., primary seal) in response to determining the flow rate of the fluid (e.g., oil) bypassing the seal is greater than a threshold flow rate. For example, in response to determining the flow rate is greater than the threshold flow rate, the controller 60 may control the electric motor 134 to drive the shaft 136 to rotate. Rotation of the shaft 136 drives the gear assembly to move the engagement element along the longitudinal axis 46 to compress the seal. The seal, in response to the longitudinal compression, may expand radially (e.g., along the radial axis 78 of the stuffing box 38′), thereby increasing the contact force between the seal and the polish rod. Accordingly, the flow rate of the fluid bypassing the seal may decrease below the threshold flow rate. In certain embodiments, in response to determining the flow rate is less than or equal to the threshold flow rate, the controller 60 may control the electric motor 134 to block rotation of the shaft 136, thereby substantially maintaining the compression of the seal.

Furthermore, in certain embodiments, the controller may determine a target contact force between the engagement element and the seal or a target electric motor torque based on the flow rate of the fluid (e.g., oil) bypassing the seal (e.g., primary seal). For example, the target contact force/electric motor torque may be higher for a higher flow rate, and the target contact force/electric motor torque may be lower for a lower flow rate. The controller may control the electric motor to achieve the target contact force/electric motor torque (e.g., based on feedback from an engagement element position sensor, based on feedback from a torque sensor, based on feedback from an electric current sensor at the actuating line, based on feedback from a force sensor, based on a contact force/electric motor torque relationship stored within the controller, etc.). In addition, in certain embodiments, the torque at the shaft may be manually controlled (e.g., alone or in combination with the automatic control provided by the controller). For example, an operator at a remote location may provide input to the user interface indicative of instructions to control the electric motor torque (e.g., based on information indicative of the flow rate of the fluid bypassing the seal, which may be presented by the user interface). Additionally or alternatively, in certain embodiments, a manual wheel may be coupled to the shaft of the electric motor. In such embodiments, an operator may manually rotate the wheel to control the torque at the shaft (e.g., based on information indicative of the flow rate of the fluid bypassing the seal, which may be presented by the user interface). While automatic and manual control is disclosed above with reference to controlling an electric motor, the techniques associated with the automatic and manual control may apply to any other suitable type of rotary actuator (e.g., pneumatic motor, hydraulic motor, etc.).

FIG. 6 is a cross-sectional view of the stuffing box 38′ of the stuffing box assembly of FIG. 5 , taken along line 6-6 of FIG. 5 . As previously discussed, the stuffing box housing 114 has a passage 138 extending through an entire longitudinal extent of the stuffing box housing 114 (e.g., extent of the stuffing box housing 114 along the longitudinal axis 46). As illustrated, the passage 138 extends along the longitudinal axis 46 of the stuffing box 38′. In the illustrated embodiment, the passage 138 has a circular cross-sectional shape. However, in other embodiments, the passage may have any other suitable cross-sectional shape (e.g., elliptical, polygonal, etc.). Furthermore, the stuffing box housing 114 has a shoulder 140 disposed along the passage 138.

As previously discussed, a seal 142 (e.g., primary seal) is disposed within the passage 138 of the stuffing box housing 114 and engaged with the shoulder 140. As used herein with regard to the shoulder, “engaged” refers to direct contact between the seal and the shoulder, or indirect contact between the seal and the shoulder, in which other element(s) are disposed between the seal and the shoulder. The shoulder 140 is configured to block movement of the seal 142 along the longitudinal axis 46 toward the threads 116 of the stuffing box housing 114. The seal 142 is configured to engage the polish rod (e.g., the polish rod at the end of the series of polish rods) while the polish rod extends through the passage 138. In the illustrated embodiment, the seal 142 is configured to extend along the circumferential axis 58 about an entire circumferential extent of the polish rod. In addition, the seal 142 is configured to expand radially (e.g., along the radial axis 78) in response to compression of the seal 142 along the longitudinal axis 46. In the illustrated embodiment, the seal 142 includes three seal elements stacked on one another along the longitudinal axis 46. However, in other embodiments, the seal may include more or fewer seal elements (e.g., 1, 2, 4, 5, 6, 7, 8, or more) stacked on one another along the longitudinal axis. In certain embodiments, each seal element has an annular shape and extends about the internal circumferential extent of the stuffing box housing. In addition, each seal element may be formed from any suitable material (e.g., polymeric material, rubber, etc.) configured to expand along the radial axis 78 in response to compression along the longitudinal axis 46. In certain embodiments, each seal element is formed as a single annular piece configured to extend about the internal circumferential extent of the stuffing box housing. However, in other embodiments, at least one seal element may be formed from multiple circumferential elements that collectively form the annular seal element. During operation of the artificial lift system, the polish rod may move upwardly and downwardly through the passage 138, and the seal 142 may engage the polish rod to substantially block flow of oil through the polish rod/stuffing box interface while enabling the polish rod to move upwardly and downwardly.

In the illustrated embodiment, the stuffing box 38′ includes a flapper assembly 144 positioned below the seal 142 (e.g., primary seal) along the longitudinal axis 46. The flapper assembly 144 includes a flapper carrier 146 and a flapper 148 pivotally coupled to the flapper carrier 146. The flapper 148 may be biased toward the flapper carrier 146. Accordingly, while the polish rod is not disposed within the passage 138 of the stuffing box housing 114, the flapper 148 may be driven to rotate to a closed position that substantially blocks oil flow through the passage 138. In addition, while the polish rod is disposed within the passage 138 (e.g., during operation of the artificial lift system), the polish rod may maintain the flapper 148 in an open position. In the illustrated embodiment, the flapper carrier 146 is positioned between the seal 142 and the shoulder 140 of the stuffing box housing 114. However, in other embodiments, the flapper carrier may be disposed at another suitable location within the passage (e.g., external threads of the flapper carrier may be engaged with internal threads of the stuffing box housing, etc.). Furthermore, while the stuffing box 38′ includes the flapper assembly 144 in the illustrated embodiment, in other embodiments, the flapper assembly may be omitted.

As previously discussed, the stuffing box 38′ includes an actuator assembly 118 having an actuator 119 and an actuator housing 120. The actuator 119 has an engagement element 150 configured to move along the longitudinal axis 46 (e.g., in a direction toward the threads 116 of the stuffing box housing 114) to compress the seal 142. As previously discussed, the seal 142 is configured to expand radially (e.g., along the radial axis 78) in response to compression of the seal 142 along the longitudinal axis 46, thereby increasing a contact force between the seal 142 and the polish rod. In the illustrated embodiment, the engagement element 150 extends about the entire circumferential extent of the seal 142 (e.g., extent of the seal 142 along the circumferential axis 58), thereby enabling the engagement element 150 to apply a substantially even force to a longitudinal end of the seal 142.

As previously discussed, the actuator 119 includes a rotary actuator, such as the electric motor disclosed above, configured to drive a shaft of the rotary actuator in rotation. The actuator 119 also includes a gear assembly 152 disposed within the actuator housing 120. The gear assembly 152 is configured to translate rotational motion of the shaft into linear movement of the engagement element 150 (e.g., movement of the engagement element 150 along the longitudinal axis 46). In the illustrated embodiment, the gear assembly 152 includes a worm gear 154 non-rotatably coupled to the shaft of the rotary actuator. For example, in certain embodiments, the worm gear may include a protrusion (e.g., hexagonal protrusion, octagonal protrusion, elliptical protrusion, star-shaped protrusion, etc.), and the shaft may include a corresponding recess. The protrusion of the worm gear may engage the recess of the shaft to non-rotatably couple the worm gear to the shaft. Furthermore, in certain embodiments, the worm gear/shaft may include other suitable engagement feature(s) (e.g., alone or in combination with the worm gear protrusion/shaft recess) to non-rotatably couple the worm gear to the shaft (e.g., a shaft protrusion/worm gear recess, pinned connection, a welded connection, etc.). Furthermore, in certain embodiments, the worm gear and the shaft may be integrally formed as a single element.

Furthermore, in the illustrated embodiment, the gear assembly 152 includes a toothed wheel 156 having external teeth 158 and internal threads 160. In addition, the worm gear 154 has spiral threads 162, and the engagement element 150 has external threads 164. The external teeth 158 of the toothed wheel 156 engage the spiral threads 162 of the worm gear 154, and the internal threads 160 of the toothed wheel 156 engage the external threads 164 of the engagement element 150. Due to the non-rotatable coupling between the shaft and the worm gear 154, rotation of the shaft drives the worm gear 154 to rotate. In addition, due to the engagement of the spiral threads 162 of the worm gear 154 with the external teeth 158 of the toothed wheel 156, rotation of the worm gear 154 drives the toothed wheel 156 to rotate about the longitudinal axis 46. Furthermore, due to the engagement of the internal threads 160 of the toothed wheel 156 with the external threads 164 of the engagement element 150, rotation of the toothed wheel 156 drives the engagement element 150 to move along the longitudinal axis 46. Accordingly, the rotary actuator (e.g., electric motor) may drive the worm gear 154 to rotate in a direction that drives the engagement element 150 to compress the seal 142, thereby increasing the contact force between the seal 142 and the polish rod. While the gear assembly 152 includes the worm gear 154 and the toothed wheel 156 in the illustrated embodiment, in other embodiments, the gear assembly may include other and/or additional suitable element(s) to convert the rotational movement of the shaft to linear movement of the engagement element (e.g., rack and pinion assembly, etc.).

In the illustrated embodiment, the stuffing box 38′ includes a first bearing 166 and a second bearing 168. The first bearing 166 is positioned on a first side of the toothed wheel 156 along the longitudinal axis 46, and the second bearing 168 is positioned on a second side of the toothed wheel 156 along the longitudinal axis 46, opposite the first side. As illustrated, the first and second bearings are disposed between the engagement element 150 and the actuator housing 120 (e.g., the body 122 of the actuator housing 120) along the radial axis 78 of the stuffing box 38′. Furthermore, the first bearing 166 is disposed between the actuator cap 128 and the toothed wheel 156 along the longitudinal axis 46, and the second bearing 168 is disposed between a shoulder 170 of the actuator housing 120 (e.g., the body 122 of the actuator housing 120) and the toothed wheel 156 along the longitudinal axis 46. The bearings are configured to facilitate rotation of the toothed wheel 156 relative to the actuator housing 120/actuator cap 128. In the illustrated embodiment, each bearing includes a single ball bearing device. However, in other embodiments, at least one bearing may include other suitable bearing device(s) (e.g., alone or in combination with the ball bearing device), such as a roller bearing device, a bushing device, other suitable type(s) of bearing device(s), or a combination thereof. For example, in certain embodiments, at least one bearing may include multiple bearing devices (e.g., of the same type and/or of different types). Furthermore, in certain embodiments, at least one of the bearings (e.g., both bearings) may be omitted.

In the illustrated embodiment, a cavity 172 is positioned radially outward from the engagement element 150. The cavity 172 is formed by the engagement element 150, the actuator housing 120 (e.g., the body 122 of the actuator housing 120), and two seals 174. The cavity 172 is configured to receive fluid (e.g., oil) bypassing the seal 142 (e.g., primary seal) via a fluid passage 176 that extends through the engagement element 150. As illustrated, the sensor is fluidly coupled to the cavity 172 via a port 178 extending through the actuator housing 120 (e.g., the body 122 of the actuator housing 120). As previously discussed, the sensor is configured to output input signal(s) to the controller. While the sensor is fluidly coupled to the cavity 172 in the illustrated embodiment, in other embodiments, the sensor may be fluidly coupled to any other suitable cavity configured to receive fluid (e.g., oil) that bypasses the seal (e.g., primary seal).

In the illustrated embodiment, the stuffing box 38′ includes a secondary seal 180 (e.g., including one or more secondary seal elements) disposed within a circumferential recess 182 of the engagement element 150 of the actuator 119. In addition, the secondary seal 180 is engaged with a shoulder 184 of the engagement element 150 to block movement of the secondary seal 180 along the longitudinal axis 46 toward the threads 116 of the stuffing box housing 114. As used herein with regard to the shoulder, “engaged” refers to direct contact between the secondary seal and the shoulder, or indirect contact between the secondary seal and the shoulder, in which other element(s) are disposed between the secondary seal and the shoulder. The secondary seal 180 is configured to engage the polish rod (e.g., the polish rod at the end of the series of polish rods) while the polish rod extends through the passage 138 of the stuffing box housing 114. In addition, the secondary seal 180 is configured to expand radially in response to compression of the secondary seal along the longitudinal axis 46 of the stuffing box 38′.

As previously discussed, the packing driver 130 has multiple apertures 186, and the threaded fasteners 132 extend through the apertures 186 and engage respective threaded recesses 188 within the engagement element 150 of the actuator 119. Each threaded fastener 132 is configured to drive the packing driver 130 to compress the secondary seal 180 along the longitudinal axis 46 in response to rotation of the threaded fastener 132. In addition, because the packing driver 130 and the threaded fasteners 132 couple the secondary seal 180 to the engagement element 150 of the actuator 119, the secondary seal 180, the packing driver 130, and the threaded fasteners 132 move with the engagement element 150 along the longitudinal axis 46. While the packing driver is coupled to the engagement element with threaded fasteners in the illustrated embodiment, in other embodiments, the packing driver may be coupled to the engagement element or another suitable component of the actuator by a threaded connection or by another suitable type of connection. Furthermore, while the stuffing box 38′ includes the secondary seal 180 in the illustrated embodiment, in other embodiments, the secondary seal may be omitted.

In the illustrated embodiment, a first annular ring 190 is positioned between the seal 142 (e.g., the primary seal) and the flapper carrier 146, and a second annular ring 192 is positioned between the seal 142 (e.g., primary seal) and the engagement element 150. Each annular ring is configured to function as a bushing between the seal 142 and the flapper carrier 146/engagement element 150. Each annular ring may be formed from any suitable material (e.g., brass, a polymeric material, etc.), and the annular ring may be formed from any suitable number of circumferential elements (e.g., 1, 2, 3, 4, or more). Furthermore, while the stuffing box 38′ includes two annular rings in the illustrated embodiment, in other embodiments, the stuffing box may include more or fewer annular rings (e.g., 0, 1, 3, 4, or more). For example, in certain embodiments, one or both of the first and second annular rings may be omitted.

FIG. 7 is another cross-sectional view of the stuffing box 38′ of the stuffing box assembly of FIG. 5 , taken along line 7-7 of FIG. 5 . As previously discussed, the external teeth 158 of the toothed wheel 156 engage the spiral threads 162 of the worm gear 154, and the internal threads 160 of the toothed wheel 156 engage the external threads 164 of the engagement element 150. Due to the non-rotatable coupling between the shaft and the worm gear 154, rotation of the shaft drives the worm gear 154 to rotate about a longitudinal axis 193 of the worm gear 154. In addition, due to the engagement of the spiral threads 162 of the worm gear 154 with the external teeth 158 of the toothed wheel 156, rotation of the worm gear 154 drives the toothed wheel 156 to rotate along the circumferential axis 58. Furthermore, due to the engagement of the internal threads 160 of the toothed wheel 156 with the external threads 164 of the engagement element 150, rotation of the toothed wheel 156 drives the engagement element 150 to move along the longitudinal axis. Accordingly, the rotary actuator (e.g., electric motor) may drive the worm gear 154 to rotate in a direction that drives the engagement element 150 to compress the seal, thereby increasing the contact force between the seal and the polish rod.

In the illustrated embodiment, the worm gear 154 is disposed within a cavity 194 of the actuator housing 120 (e.g., the body 122 of the actuator housing 120). In addition, the worm gear 154 is rotatably supported within the cavity 194 by a first worm gear bearing 196 and a second worm gear bearing 198. Each worm gear bearing is configured to engage the actuator housing 120 (e.g., the body 122 of the actuator housing 120) and the worm gear 154. As such, each worm gear bearing is configured to enable the worm gear 154 to rotate about the longitudinal axis 193 of the worm gear 154 relative to the actuator housing 120 and to substantially block radial movement of the worm gear 154 (e.g., along a radial axis 199 of the worm gear 154) relative to the actuator housing 120 (e.g., the body 122 of the actuator housing 120). In certain embodiments, each worm gear bearing includes a single ball bearing device. However, in other embodiments, at least one worm gear bearing may include other suitable bearing device(s) (e.g., alone or in combination with the ball bearing device), such as a roller bearing device, a bushing device, other suitable type(s) of bearing device(s), or a combination thereof. For example, in certain embodiments, at least one worm gear bearing may include multiple bearing devices (e.g., of the same type and/or of different types). Furthermore, in certain embodiments, at least one of the worm gear bearings (e.g., both worm gear bearings) may be omitted.

In the illustrated embodiment, the actuator housing 120 (e.g., the body 122 of the actuator housing 120) has a shoulder 200, and the first worm gear bearing 196 is engaged with the shoulder 200. In addition, the worm gear 154 has a shoulder 202, and the shoulder 202 is engaged with the first worm gear bearing 196. Accordingly, longitudinal movement of the first worm gear bearing 196 (e.g., along the longitudinal axis 193 of the worm gear 154) in a direction toward the shaft is blocked by the shoulder 200 of the actuator housing 120, and longitudinal movement of the worm gear 154 (e.g., along the longitudinal axis 193 of the worm gear 154) in the direction toward the shaft is blocked by the first worm gear bearing 196.

Furthermore, in the illustrated embodiment, the actuator housing 120 has a retainer cap 204 coupled to the body 122 of the actuator housing 120. In the illustrated embodiment, the retainer cap 204 is coupled to the actuator housing body 122 by a threaded connection. However, in certain embodiments, the retainer cap may be coupled to the actuator housing body via other suitable type(s) of connection(s) (e.g., alone or in combination with the threaded connection), such as a fastener connection, other suitable type(s) of connection(s), or a combination thereof. The retainer cap 204 may be removed from the actuator housing body 122 to facilitate insertion and removal of the worm gear 154, the first worm gear bearing 196, and the second worm gear bearing 198. In the illustrated embodiment, the retainer cap 104 has a shoulder 206 configured to engage the second worm gear bearing 198, thereby blocking longitudinal movement of the second worm gear bearing 198 (e.g., along the longitudinal axis 193 of the worm gear 154) in a direction away from the shaft.

Furthermore, in the illustrated embodiment, a bushing 208 is disposed between the worm gear 154 and the retainer cap 204 along the radial axis 199 of the worm gear 154. The bushing 208 is configured to facilitate rotation of the worm gear 154 about the longitudinal axis 193 of the worm gear 154 and to substantially block movement of the worm gear 154 relative to the retainer cap 204 along the radial axis 199 of the worm gear 154. While the stuffing box 38′ includes one bushing 208 in the illustrated embodiment, in other embodiments, the stuffing box may include more or fewer bushings (e.g., 0, 2, 3, 4, etc.), and/or one or more other suitable bearing devices may be disposed between the worm gear and the retainer cap. Furthermore, while the worm gear 154 is retained by the retainer cap 204 in the illustrated embodiment, in other embodiments, the worm gear may be retained by other suitable device(s)/element(s) (e.g., alone or in combination with the retainer cap), such as a second retainer cap positioned at the opposite longitudinal end of the worm gear, clamp(s), pin(s), other suitable device(s)/element(s), or a combination thereof

In the embodiments disclosed above with regard to FIGS. 3-7 , the shoulder of the stuffing box housing (e.g., which engages the primary seal) is integrally formed with a main body of the stuffing box housing. However, in other embodiments, the shoulder may be formed on a secondary element of the stuffing box housing and coupled to the main body of the stuffing box housing. For example, in certain embodiments, the secondary element may have external threads configured to interface with internal threads of the main body, thereby forming the stuffing box housing. Additionally or alternatively, the secondary element may be coupled to the main body by other suitable connection(s) (e.g., alone or in combination with the threaded connection), such as a pinned connection and/or a welded connection.

While only certain features have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f). 

1. A stuffing box assembly for an artificial lift system, comprising: a stuffing box, comprising: a stuffing box housing having a passage extending through an entire longitudinal extent of the stuffing box housing, wherein the stuffing box housing has a shoulder disposed along the passage; a seal disposed within the passage of the stuffing box housing and engaged with the shoulder, wherein the seal is configured to engage a polish rod while the polish rod extends through the passage, and the seal is configured to expand radially in response to compression of the seal along a longitudinal axis of the stuffing box; and an actuator having an engagement element configured to move along the longitudinal axis to compress the seal; and a controller comprising a processor and a memory, wherein the controller is communicatively coupled to the actuator, the controller is configured to determine a flow rate of fluid bypassing the seal based on one or more input signals, and the controller is configured to control the actuator based on the flow rate of the fluid bypassing the seal.
 2. The stuffing box assembly of claim 1, comprising an actuating line coupled to the actuator and configured to facilitate control of the actuator from a location remote from the stuffing box.
 3. The stuffing box assembly of claim 2, wherein the actuator comprises a piston, the actuating line comprises an actuating fluid line, and the actuating fluid line is configured to enable flow of actuating fluid to the actuator to drive the piston to move the engagement element along the longitudinal axis to compress the seal.
 4. The stuffing box assembly of claim 3, comprising a valve assembly fluidly coupled to the actuating fluid line and communicatively coupled to the controller, wherein the controller is configured to control the valve assembly to control flow of the actuating fluid to the actuator.
 5. The stuffing box assembly of claim 2, wherein the actuator comprises an electric motor, the actuating line comprises an electrical line, the electrical line is configured to provide electrical power to the electric motor, and the electric motor is configured to drive the engagement element along the longitudinal axis to compress the seal in response to receiving the electrical power.
 6. The stuffing box assembly of claim 5, wherein the actuator comprises a gear assembly configured to translate rotational motion of a shaft of the electric motor into linear movement of the engagement element along the longitudinal axis.
 7. The stuffing box assembly of claim 1, wherein the stuffing box comprises a secondary seal disposed within a circumferential recess of the actuator and engaged with a shoulder of the actuator, the secondary seal is configured to engage the polish rod while the polish rod extends through the passage of the stuffing box housing, and the secondary seal is configured to expand radially in response to compression of the secondary seal along the longitudinal axis of the stuffing box.
 8. The stuffing box assembly of claim 7, wherein the stuffing box comprises a packing nut having external threads, the actuator has corresponding internal threads configured to engage the external threads of the packing nut, and the packing nut is configured to compress the secondary seal along the longitudinal axis in response to rotation of the packing nut.
 9. The stuffing box assembly of claim 7, wherein the stuffing box comprises: a packing driver having a plurality of apertures; and a plurality of threaded fasteners configured to extend through the plurality of apertures; wherein the actuator comprises a plurality of threaded recesses, the plurality of threaded fasteners are configured to engage the plurality of threaded recesses, and each threaded fastener of the plurality of threaded fasteners is configured to drive the packing driver to compress the secondary seal along the longitudinal axis in response to rotation of the threaded fastener.
 10. The stuffing box assembly of claim 1, comprising a sensor communicatively coupled to the controller, wherein the sensor is fluidly coupled to a cavity configured to receive the fluid bypassing the seal, and the sensor is configured to output the one or more input signals to the controller.
 11. The stuffing box assembly of claim 1, wherein the controller is configured to control the actuator to compress the seal in response to determining the flow rate of the fluid bypassing the seal is greater than a threshold flow rate.
 12. The stuffing box assembly of claim 1, comprising a user interface communicatively coupled to the controller, wherein the controller is configured to control the user interface to inform an operator in response to determining the flow rate of the fluid bypassing the seal is greater than a threshold flow rate.
 13. A stuffing box for an artificial lift system, comprising: a stuffing box housing having a passage extending through an entire longitudinal extent of the stuffing box housing, wherein the stuffing box housing has a shoulder disposed along the passage; a seal disposed within the passage of the stuffing box housing and engaged with the shoulder, wherein the seal is configured to engage a polish rod while the polish rod extends through the passage, and the seal is configured to expand radially in response to compression of the seal along a longitudinal axis of the stuffing box; and an actuator assembly comprising an actuator and an actuator housing, wherein the actuator housing is coupled to the stuffing box housing, and the actuator comprises: an engagement element configured to move along the longitudinal axis to compress the seal; and a gear assembly disposed within the actuator housing and configured to translate rotational motion of a shaft into linear movement of the engagement element along the longitudinal axis.
 14. The stuffing box of claim 13, wherein the actuator comprises a rotary actuator, the rotary actuator comprises the shaft, and the rotary actuator is configured to drive the shaft in rotation.
 15. The stuffing box of claim 13, wherein the gear assembly comprises: a worm gear non-rotatably coupled to the shaft of the rotary actuator, wherein the worm gear has spiral threads; and a toothed wheel having external teeth and internal threads, wherein the external teeth are configured to engage the spiral threads of the worm gear, the engagement element has external threads, and the internal threads of the toothed wheel are configured to engage the external threads of the engagement element.
 16. The stuffing box of claim 13, comprising a first bearing and a second bearing, wherein the first bearing is positioned on a first side of the toothed wheel along the longitudinal axis, the second bearing is positioned on a second side of the toothed wheel along the longitudinal axis, opposite the first side, and the first and second bearings are disposed between the engagement element and the actuator housing along a radial axis of the stuffing box.
 17. The stuffing box of claim 13, comprising a secondary seal disposed within a circumferential recess of the engagement element of the actuator, wherein the secondary seal is engaged with a shoulder of the engagement element of the actuator, the secondary seal is configured to engage the polish rod while the polish rod extends through the passage of the stuffing box housing, and the secondary seal is configured to expand radially in response to compression of the secondary seal along the longitudinal axis of the stuffing box.
 18. A stuffing box for an artificial lift system, comprising: a stuffing box housing having a passage extending through an entire longitudinal extent of the stuffing box housing, wherein the stuffing box housing has a shoulder disposed along the passage; a seal disposed within the passage of the stuffing box housing and engaged with the shoulder, wherein the seal is configured to engage a polish rod while the polish rod extends through the passage, and the seal is configured to expand radially in response to compression of the seal along a longitudinal axis of the stuffing box; and an actuator assembly comprising an actuator and an actuator housing, wherein the actuator housing is coupled to the stuffing box housing, and the actuator comprises: an engagement element configured to move along the longitudinal axis to compress the seal; and a piston configured to drive the engagement element to move along the longitudinal axis to compress the seal in response to receiving actuating fluid within a cavity formed by the piston and the actuator housing.
 19. The stuffing box of claim 18, comprising a cavity seal disposed between the piston and the actuator housing along a radial axis of the stuffing box, wherein the seal is configured to substantially block actuating fluid flow out of the cavity.
 20. The stuffing box of claim 18, comprising a secondary seal disposed within a circumferential recess of the actuator and engaged with a shoulder of the actuator, wherein the secondary seal is configured to engage the polish rod while the polish rod extends through the passage of the stuffing box housing, and the secondary seal is configured to expand radially in response to compression of the secondary seal along the longitudinal axis of the stuffing box. 